The present invention relates to a novel production method of tetrakis(pentafluorophenyl)borate derivatives using pentafluorophenylmagnesium derivatives.
The boron derivatives obtainable according to the invention are very important substances as intermediates of cocatalysts for the cationic complex polymerization reaction.
In recent years, scientific literatures or patents on the studies, in which cationic complexes are generated using tetrakis(pentafluorophenyl)borate derivatives and cyclopentadienyl transition metal complexes, so-called metallocene derivatives, and these are used as catalysts for the polymerization reaction, have increased remarkably. For example, there are Macromol. Chem. Rapid Commun., 2, p.p. 663-667 (1991), etc. Conventionally, however, tetrakis(pentafluorophenyl)borate derivatives have been produced through a process using pentafluorophenyllithium derived from bromopentafluorobenzene as the source of pentafluorophenyl group.
Moreover, pentafluorophenyllithium tends to decompose as the temperature increases and further it decomposes explosively when the temperature exceeds -20.degree. C., hence, usually, it is generated at a temperature as very low as -70.degree. C. and used at the same temperature.
For this reason, installations for low temperature were required, posing a significant problem in the aspect of cost and a problem in the aspect of safety on production as well.
On the other hand, even if attempting to produce tetrakis(pentafluorophenyl)borate derivatives by the same method as the production method of sodium tetraphenylborate described in Experimental Chemistry Series, Vol. 12, "Organometallic Chemistry", p. 307 (published on Mar. 20, 1976, etitor: Corporation Japan Chemical Society, publisher: Maruzen Co., Ltd.), they could not be produced in good yield.
In view of said situation, the inventors investigated extensively on such a production method that pentafluorophenylmagnesium derivatives are used as the source of pentafluorophenyl group on the production of tetrakis(pentafluorophenyl)borate derivatives and very low temperature is unnecessary to be used, leading to the invention.